samcolt

HAD a 2000 5.3 Silverado 4-speed reg cab and drove it coast to coast and border to border and always got 20-21mpg on reg gas.

Bought a new 2011 Silverado 5.3 reg cab, same rear end but 6peed tranny and havent hit 17mpg yet in 3000 miles, reg gas. 16-16.5 is the best I've seen--mostly interstate at 70+

Dealer has me keeping a log, but log or no log, is this what I can expect with the newer model??

Any info is appreciated. I hate to go to the dealer with no comparisons other than my old truck.

AKlowriderZ71

iTrader: (22)

I've never owned a new truck with the 6L80E, so I can't say exactly what you should expect, but.......

My 2001 5.3 with the 4L60E, 3.73 gears, and 32" tires got 19 mpg before tuned, and 21 mpg after tuned. (all before being supercharged & cammed).

Also, every single new vehicle I've owned got noticably better mpg's with every gas tank fillup. Somewhere between 12-15,000 miles, they all leveled off.

With that said, and knowing that your brand new engine is still tight, and breaking in, you are getting 16.5 mpg. I'd guess that once it's all broken in and running a little bit looser, that you'll get 19 mpg or better.

BrutalSierra

iTrader: (1)

I Concur!

JoeyGC5

iTrader: (24)

I had to be very gentle in the driving of my 2011 K1500 Chevy to get 18.5-19mpg. If I drove it like I use to drive my 2001 K1500 I would get 15mpg. Changing the stock tune and messing with alot of the trans functions has helped my 2011 truck gain mileage allowing me to hit right at 20-21mpg under normal "sane" highway driving, I have about 13k on the 2011 now.

BrutalSierra

iTrader: (1)

What wheels are you running?

My truck is crewcab. with 6.2L motor and with the factory 20's i would get over 20mpg on freeway with a tune and cai.

i now have some 17's and i'm knocking down some killer mpgs on the freeway.

I reset my mileage each tank so i learn how the truck likes to be driven for mileage.
i also have 3.42 gears which suck with the 6spd. I'm switching to 4.10's shortly as i don't drive much freeway.

JAVI05

i have a 09 5.3 with the 6 speed and 3.42..dropped on 22's crew cab.. i got a tune and turned off afm... i get 16.5 city and got 22 mpgs highway driving 70+... 22mpgs hwy surprised the crap outta me with a good tune also,..

i would recommend you break your engine in first before actually looking at real mpg's.

samcolt

Thanks guys.
My 2000 LS had : 16" factory tires- aluminum wheels, no tune, 3.43 rear, aftermarket K&N intake, Hooker dual chamber single in - dual out. Otherwise stock. 15.3 1/4 mile

The 2011 LT has: 17" stock tires- chrome steel wheels, 3.43 rear and totally stock.

Maybe I need a few thousand more miles before I get nervous, but the first tank and last tank load shows no mileage change at 3K miles.

Troponin

I had a 2009 Sierra with the 5.3. Here in Texas the speed limits are 70 almost everywhere. I couldn't get better than 16mpg on a long highway trip, and averaged 14.5. Had 20,000 miles on the truck.

That said, the 5.3 can't shift in to 4 cylinders for the economy at speeds above 55 and any hills etc shift it out too. I rarely saw it in 4 cylinders. Not sure of this is the same engine you're talking about, but this is my expirence with the 5.3. If I were back in my home town of pa, I think it would have seen 4 cylinders on the highway a lot more

oldred95

They could have accomplished more by efficiently using DFCO then the cost and wasted money that went into engineering the active fuel management BS and then having to pay to fix them under warranty when the lifters collapse among other things.

I was once told the way they actually test for rated fuel mileage is on a dyno of some sort that is supposed to simulate driving. If you are inside a room just turning the rear wheels its never going to be the same as fighting a 40 mph head wind up hill or being in and out of the gas trying to find an opening to pass the old geezer in front of you. Its just a rating that under perfect conditions the truck may reach but for the most part it won't ever see it.

iregret

iTrader: (4)

Was your 2000 2wd and your 2011 4wd?

I had a 2002 that consistently got 19-20mpg. Now I have a 2000 that gets 16.5mpg. The only difference between the two is the 2002 was 2wd and the 2000 is 4wd. I didn't realize it would make that much of a difference.